A standard ink applicator for a printing machine or the like has an ink applicator that normally sits atop a transfer roll. The applicator forms a thin uniform coat of ink on the transfer roll which is then applied to the actual printing roll.
Such an applicator typically includes a pair of end parts that are spaced longitudinally apart and a pair of bars extending longitudinally parallel to each other between the end parts and each carrying a flexible applicator blade. The end parts, bars, and blades form a compartment that is open downward through a gap defined between confronting but spaced free edges of the blades. In use these blades ride lightly on the surface of the transfer roll and so that ink in the compartment can flow onto the transfer roll, being doctored into a thin layer by the trailing blade.
While such an arrangement works very well, when the applicator has to be changed, for instance because it needs servicing or different ink or tint is to be applied, it is standard practice to run the applicator dry. Once it is empty, it can be lifted off the transfer roll and switch for a new one that is then filled and used.
If the applicator is lifted off the transfer roll while still full there is usually a mess. Even though the ink is typically quite viscous, it can still flow out the bottom of the applicator, normally fouling the machine. This procedure is not normally preferred; instead it is better to shut off the ink supply and run the printer, thereby wasting ink and paper, until the applicator is empty.